Cement production involves the processing of raw materials in a kiln. The raw materials for a cement kiln are usually limestone and clays. Rotary kilns are commonly used for processing and consist of a horizontally disposed revolving, cylindrical tube internally lined with refractory material. The rotary kiln refractory lining typically is of a brick construction. The kiln itself is divided into a number of heat zones in which raw materials are processed by flame heating. The rotary kiln flames are maintained by the combustion of fuels such as liquid hydrocarbons, coal, and natural gas. The resulting product of kiln processing is cement clinker. A by-product of the cement rotary kiln process is the formation of kiln rings on the refractory lining.
The culmination of kiln rings is an unwanted build-up on the refractory lining which necessitates periodic shutdown of the kiln operation for clean-up and removal purposes. During clean-up, these rings present a danger to workmen and machinery used in their removal. Specifically, the kiln, being a horizontally disposed cylindrical tube, will have some of the kiln ring build-up disposed above the workmen who must enter the kiln during clean-up. There is a great danger that the overhead ring material when disturbed may fall upon those working in the internal kiln areas.
Protection from overhead falling materials has been previously disclosed in, for example, the Joseph patent, U.S. Pat. No. 3,115,754. The Joseph U.S. Pat. No. 3,115,754 relates to an apparatus for the purpose of supporting the roofs of underground excavations, such as the roofs of mineral mines and tunnels driven into ground strata. The purpose of the roof support is to give protection to workers and equipment against material which falls from the roof and sides of the excavation. The apparatus disclosed in the Joseph patent comprises a plurality of cage-type roof supporting, interconnected units having power means for independently elevating and lowering the units so as to conform to an undulating confinement. The Joseph apparatus also includes a collapsible structure for use in supporting overhead roofing during underground excavation.